Immunomodulatory Effects of Colistin on Macrophages in Rats by Activating the p38/MAPK Pathway

The Interplay between Antibiotics and the Host Immune Response in Sepsis: From Basic Mechanisms to Clinical Considerations: A Comprehensive Narrative Review

Sepsis poses a significant global health challenge due to immune system dysregulation. This narrative review explores the complex relationship between antibiotics and the immune system, aiming to clarify the involved mechanisms and their clinical impacts. From pre-clinical studies, antibiotics exhibit various immunomodulatory effects, including the regulation of pro-inflammatory cytokine production, interaction with Toll-Like Receptors, modulation of the P38/Pmk-1 Pathway, inhibition of Matrix Metalloproteinases, blockade of nitric oxide synthase, and regulation of caspase-induced apoptosis. Additionally, antibiotic-induced alterations to the microbiome are associated with changes in systemic immunity, affecting cellular and humoral responses. The adjunctive use of antibiotics in sepsis patients, particularly macrolides, has attracted attention due to their immune-regulatory effects. However, there are limited data comparing different types of macrolides. More robust evidence comes from studies on community-acquired pneumonia, especially in severe cases with a hyper-inflammatory response. While studies on septic shock have shown mixed results regarding mortality rates and immune response modulation, conflicting findings are also observed with macrolides in acute respiratory distress syndrome. In conclusion, there is a pressing need to tailor antibiotic therapy based on the patient's immune profile to optimize outcomes in sepsis management.

Anti-inflammatory and immunoregulatory effects of colistin sulphate on human PBMCs

In previous studies, CST has been identified as having an immunostimulatory effect on Caenorhabditis elegans and macrophage of rats. Here, we further investigated its immunomodulatory effects on human peripheral blood mononuclear cells (PBMCs). LPS-stimulated PBMCs inflammatory model was established. Flow cytometry was applied to measure phagocytosis of PBMCs. Cytokine mRNA and protein expression levels of LPS-stimulated PBMCs with or without CST were measured by qRT-PCR and ELISA. The transcriptomic profile of CST-treated PBMCs was investigated by RNA-sequencing. Gene Ontology (GO) and Kyoto Encylopedia of Genes and Genomes (KEGG) were applied to find potential signalling pathways. PBMCs showed a significant increase in phagocytic activity at 6 h after being incubated with CST at the concentration of 10 μg/mL. In the presence of LPS, CST maintained and promoted the expression of TNF-α and chemokine CCL24. The content of pro-inflammatory cytokines, such as IL-1β, IL-6 and IFN-γ, which were released from LPS-stimulated PBMCs, was reduced by CST at 6 h. Anti-inflammatory cytokines, such as IL-4, IL-13 and TGF-β1, were significantly increased by CST at 24 h. A total of 277 differentially expressed immune-related genes (DEIRGs) were detected and cytokine-cytokine receptor interaction was highly enriched. CST presented obvious anti-inflammatory and immunoregulatory effects in LPS-induced PBMCs inflammatory model not only by improving the ability of PBMCs to clear pathogens but also by decreasing pro-inflammatory cytokines and increasing anti-inflammatory cytokines. And the mechanism may be related to cytokine-cytokine receptor interaction.

Amentoflavone Mitigates Cyclophosphamide-Induced Pulmonary Toxicity: Involvement of -SIRT-1/Nrf2/Keap1 Axis, JAK-2/STAT-3 Signaling, and Apoptosis

Background and objectives: Cyclophosphamide (CPA) is an alkylating agent that is used for the management of various types of malignancies and as an immunosuppressive agent for the treatment of immunological disorders. However, its use is limited by its potential to cause a wide range of pulmonary toxicities. Amentoflavone (AMV) is a flavonoid that had proven efficacy in the treatment of disease states in which oxidative stress, inflammation, and apoptosis may play a pathophysiologic role. This study investigated the potential ameliorative effects of the different doses of AMV on CPA-induced pulmonary toxicity, with special emphasis on its antioxidant, anti-inflammatory, and apoptosis-modulating effects. Materials and methods: In a rat model of CPA-induced pulmonary toxicity, the effect of AMV at two dose levels (50 mg/kg/day and 100 mg/kg/day) was investigated. The total and differential leucocytic counts, lactate dehydrogenase activity, and levels of pro-inflammatory cytokines in the bronchoalveolar lavage fluid were estimated. Also, the levels of oxidative stress parameters, sirtuin-1, Keap1, Nrf2, JAK2, STAT3, hydroxyproline, matrix metalloproteinases 3 and 9, autophagy markers, and the cleaved caspase 3 were assessed in the pulmonary tissues. In addition, the histopathological and electron microscopic changes in the pulmonary tissues were evaluated. Results: AMV dose-dependently ameliorated the pulmonary toxicities induced by CPA via modulation of the SIRT-1/Nrf2/Keap1 axis, mitigation of the inflammatory and fibrotic events, impaction of JAK-2/STAT-3 axis, and modulation of the autophagic and apoptotic signals. Conclusions: AMV may open new horizons towards the mitigation of the pulmonary toxicities induced by CPA.

Dual functional therapeutics: mitigating bacterial infection and associated inflammation

The emergence of antimicrobial resistance, coupled with the occurrence of persistent systemic infections, has already complicated clinical therapy efforts. Moreover, infections are also accompanied by strong inflammatory responses, generated by the host's innate and adaptive immune systems. The closely intertwined relationship between bacterial infection and inflammation has multiple implications on the ability of antibacterial therapeutics to tackle infection and inflammation. Particularly, uncontrolled inflammatory responses to infection can lead to sepsis, a life-threatening physiological condition. In this review, we discuss dual-functional antibacterial therapeutics that have potential to be developed for treating inflammation associated with bacterial infections. Immense research is underway that aims to develop new therapeutic agents that, when administered, regulate the excess inflammatory response, i.e. they have immunomodulatory properties along with the desired antibacterial activity. The classes of antibiotics that have immunomodulatory function in addition to antibacterial activity have been reviewed. Host defense peptides and their synthetic mimics are amongst the most sought-after solutions to develop such dual-functional therapeutics. This review also highlights the important classes of peptidomimetics that exhibit both antibacterial and immunomodulatory properties.

Highly different effects of phage therapy and antibiotic therapy on immunological responses of chickens infected with Salmonella enterica serovar Typhimurium

The appearance of bacteria resistant to most or even all known antibiotics has become a serious medical problem. One such promising and effective alternative form of therapy may be the use of phages, the administration of which is considered to be safe and highly effective, especially in animals with drug-resistant infections. Although there have been no reports to date suggesting that bacteriophages can cause any severe complications or adverse effects, we still know little about their interactions with animal organisms, especially in the context of the functioning of the immune system. Therefore, the aim of the present study was to compare the impact of the application of selected bacteriophages and antibiotics (enrofloxacin and colistin), commonly used in veterinary medicine, on immune functions in Salmonella enterica serovar Typhimurium-infected chickens. The birds were infected with S. Typhimurium and then treated with a phage cocktail (14 days), enrofloxacin (5 days), or colistin (5 days). The concentrations of a panel of pro-inflammatory cytokines (IL-1β, IL-6, IFN-γ, IL-8, and IL-12) and cytokines that reveal anti-inflammatory effects (IL-10 and IL-4), the percentage of lymphocytes, and the level of stress hormones (corticosterone and cortisol), which significantly modulate the immune responses, were determined in different variants of the experiment. The phage cocktail revealed anti-inflammatory effects when administered either 1 day after infection or 2 days after S. Typhimurium detection in feces, as measured by inhibition of the increase in levels of inflammatory response markers (IL-1β, IL-6, IFN-γ, IL-8, and IL-12). This was also confirmed by increased levels of cytokines that exert an anti-inflammatory action (IL-10 and IL-4) following phage therapy. Moreover, phages did not cause a negative effect on the number and activity of lymphocytes’ subpopulations crucial for normal immune system function. These results indicate for the first time that phage therapy not only is effective but also can be used in veterinary medicine without disturbing immune homeostasis, expressed as cytokine imbalance, disturbed percentage of key immune cell subpopulations, and stress axis hyperactivity, which were observed in our experiments as adverse effects accompanying the antibiotic therapy.

Nanocarriers for effective delivery: modulation of innate immunity for the management of infections and the associated complications

Innate immunity is the first line of defense against invading pathogens. Innate immune cells can recognize invading pathogens through recognizing pathogen-associated molecular patterns (PAMPs) via pattern recognition receptors (PRRs). The recognition of PAMPs by PRRs triggers immune defense mechanisms and the secretion of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6. However, sustained and overwhelming activation of immune system may disrupt immune homeostasis and contribute to inflammatory disorders. Immunomodulators targeting PRRs may be beneficial to treat infectious diseases and their associated complications. However, therapeutic performances of immunomodulators can be negatively affected by (1) high immune-mediated toxicity, (2) poor solubility and (3) bioactivity loss after long circulation. Recently, nanocarriers have emerged as a very promising tool to overcome these obstacles owning to their unique properties such as sustained circulation, desired bio-distribution, and preferred pharmacokinetic and pharmacodynamic profiles. In this review, we aim to provide an up-to-date overview on the strategies and applications of nanocarrier-assisted innate immune modulation for the management of infections and their associated complications. We first summarize examples of important innate immune modulators. The types of nanomaterials available for drug delivery, as well as their applications for the delivery of immunomodulatory drugs and vaccine adjuvants are also discussed.

A New Functional Screening Platform Identifies Colistin Sulfate as an Enhancer of Natural Killer Cell Cytotoxicity

Simple Summary

The use of small compounds in cancer immunotherapy has been limited so far. Her we screen for drugs that enhanced the ability of immune cells to kill tumor cells and identified the molecule Colistin Sulfate as a booster of immune activity.

Abstract

Due to their crucial role in tumor immunity, NK cells have quickly became a prime target for immunotherapies, with the adoptive transfer of NK cells and the use of NK cell engagers quickly moving to the clinical stage. On the other hand, only a few studies have focused on small molecule drugs capable of unleashing NK cells against cancer. In this context, repurposing small molecules is an attractive strategy to identify new immunotherapies from already approved drugs. Here, we developed a new platform to screen small molecule compounds based on a high-throughput luciferase-release cytotoxicity assay. We tested 1200 FDA approved drugs from the Prestwick Chemical Library, to identify compounds that increase NK cells’ cytotoxic potential. We found that the antibiotic colistin sulfate increased the cytotoxicity of human NK cells towards cancer cells. The effect of colistin was short lived and was not observed when NK cells were pretreated with the drug, showing how NK cell activity was potentiated only when the compound was present at the time of recognition of cancer cells. Further studies are needed to uncover the mechanism of action and the pre-clinical efficacy of colistin sulfate in mouse cancer models.

Gut Microbiota Alteration Influences Colorectal Cancer Metastasis to the Liver by Remodeling the Liver Immune Microenvironment

Background/Aims

This study aimed to explore the effect of gut microbiota-regulated Kupffer cells (KCs) on colorectal cancer (CRC) liver metastasis.

Methods

A series of in vivo and in vitro researches were showed to demonstrate the gut microbiota and its possible mechanism in CRC liver metastasis.

Results

Fewer liver metastases were identified in the ampicillin-streptomycin-colistin and colistin groups. Increased proportions of Parabacteroides goldsteinii, Bacteroides vulgatus, Bacteroides thetaiotaomicron, and Bacteroides uniformis were observed in the colistin group. The significant expansion of KCs was identified in the ampicillin-streptomycin-colistin and colistin groups. B. vulgatus levels were positively correlated with KC levels. More liver metastases were observed in the vancomycin group. An increased abundance of Parabacteroides distasonis and Proteus mirabilis and an obvious reduction of KCs were noted in the vancomycin group. P. mirabilis levels were negatively related to KC levels. The number of liver metastatic nodules was increased in the P. mirabilis group and decreased in the B. vulgatus group. The number of KCs decreased in the P. mirabilis group and increased in the B. vulgatus group. In vitro, as P. mirabilis or B. vulgatus doses increased, there was an opposite effect on KC proliferation in dose- and time-dependent manners. P. mirabilis induced CT26 cell migration by controlling KC proliferation, whereas B. vulgatus prevented this migration.

Conclusions

An increased abundance of P. mirabilis and decreased amount of B. vulgatus play key roles in CRC liver metastasis, which might be related to KC reductions in the liver.

Tumor-associated macrophage derived IL-6 enriches cancer stem cell population and promotes breast tumor progression via Stat-3 pathway

BACKGROUND

Cancer stem cells (CSCs) play crucial role in tumor progression, drug resistance and relapse in various cancers. CSC niche is comprised of various stromal cell types including Tumor-associated macrophages (TAMs). Extrinsic ques derived from these cells help in maintenance of CSC phenotype. TAMs have versatile roles in tumor progression however their function in enrichment of CSC is poorly explored.

METHODS

Mouse macrophages (RAW264.7) cells were activated by interaction with conditioned media (CM) of murine breast cancer cells (4T1) into TAMs and the effect of activated macrophage (TAM) derived factors was examined on enrichment of cancer stem cells (CSCs) and tumor growth using in vitro and in vivo models.

RESULTS

In this study, we report that macrophages upon interaction with breast cancer cells activate tumor promoting function and exhibit differential expression of various proteins as shown by secretome analysis using proteomics studies. Based on secretome data, we found that Interleukin-6 (IL-6) is one of the up-regulated genes expressed in activated macrophages. Further, we confirm that TAMs produce high levels of IL-6 and breast cancer cell derived factors induce IL-6 production in activated macrophages via p38-MAPK pathway. Furthermore, we demonstrate that tumor activated macrophages induce enrichment of CSCs and expression of CSC specific transcription factors such as Sox-2, Oct-3/4 and Nanog in breast cancer cells. We further prove that TAM derived IL-6 plays a key role in TAM mediated CSC enrichment through activation of Signal transducer and activator of transcription 3 (STAT-3) signaling. TAM derived IL-6 influences breast cancer cell migration and angiogenesis. Moreover, our in vivo findings indicated that TAM derived IL-6 induces CSC population and resulting tumor growth in breast cancer.

CONCLUSION

These finding provide evidence that TAM derived IL-6 plays a major role in CSC enrichment and tumor progression in breast cancer and IL-6 and its regulated signalling network may act as potential therapeutic target for management of breast cancer.

Tanshinone IIA Inhibits Tissue Factor Expression Induced by Thrombin in Human Umbilical Vein Endothelial Cells via PAR-1 and p38 MAPK Signaling Pathway

BACKGROUND

The potential signaling pathway of TSA suppressing TF expression induced by thrombin was unknown. Thus, the transcription of TF in HUVECs and the expressions of DCF, phospho-p38 MAPK, NADPH oxidase 4, PAR-1, and NF-κB were detected in our study.

METHODS

HUVECs were randomly divided into control group, thrombin-treated group (with 5 U/mL of thrombin), and 4 TSA-treated groups (with 5 U/mL of thrombin plus TSA with 4 different concentrations of 1 μg/mL, 10 μg/mL, 100 μg/mL, and 1 mg/mL, respectively).

RESULTS

After incubation with thrombin for 6 h at 37°C, the results showed increased TF mRNA, TF procoagulant activity, and antigen of TF in HUVECs of thrombin-treated group (p < 0.01); however, they were restored by TSA in a dose-dependent manner (p < 0.01). In addition, reactive oxygen species (ROS), phospho-p38 MAPK, NADPH oxidase 4, NF-κB, and PAR-1 expressed more intensively, and phosphorylated Akt decreased obviously in HUVECs after thrombin stimulation (p < 0.01); however, they were reversed to different extents by TSA in a dose-dependent manner (p < 0.01).

CONCLUSIONS

Study suggests that TSA inhibits TF expression induced by thrombin in cultured HUVECs, and the potential signaling pathway of which is TSA interrupts the activation of PAR-1 and NADPH oxidase as well as derivative ROS generation, thereafter suppresses the activation of NF-κB, the upstream signal molecule of TF, via hampering phosphorylation of p38 MAPK and dephosphorylation of Akt, and finally inhibits thrombin-induced TF overexpression.

Review of the Efficacy and Mechanisms of Traditional Chinese Medicines as a Therapeutic Option for Ionizing Radiation Induced Damage

Ionizing radiation damage refers to acute, delayed, or chronic tissue damage associated with ionizing radiation. Specific or effective therapeutic options for systemic injuries induced by ionizing radiation have not been developed. Studies have shown that Chinese herbal Medicine or Chinese Herbal Prescription exhibit preventive properties against radiation damage. These medicines inhibit tissue injuries and promote repair with very minimal side effects. This study reviews traditional Chinese herbal medicines and prescriptions with radiation protective effects as well as their mechanisms of action. The information obtained will guide the development of alternative radioprotectants.

Immunomodulatory Effect of Colistin and its Protective Role in Rats with Methicillin-Resistant Staphylococcus aureus-induced Pneumonia

Objectives: Colistin is the last resort of antimicrobials against multi-drug resistant Gram-negative pathogens. Previous studies in Caenorhabditis elegans and macrophages of rats have suggested that colistin possesses the immunomodulatory properties by acting p38/MAPK pathway. Here, we aimed to confirm the immunomodulatory role of colistin in animal models. Methods: Rat model of Methicillin-resistant Staphylococcus aureus (MRSA)-induced pneumonia was established. Plasma concentrations of proinflammatory cytokines, quantitative bacteriology, histology and immunohistochemistry of lungs were assessed to compare the immunomodulatory properties of colistin pre-administration. Results: The numbers of white blood cells and granulocytes were significantly increased in the 9 mg/kg colistin pre-administration group at 72 h after infection. Levels of TNF-α, IL-6 and IL-1β in plasma after colistin pre-administration were lower compared with the infected group without treatment. Colistin pre-treatment resulted in lower bacterial counts, a dramatic decrease of cytokines and improved histopathological injury in infected lung tissues compared with the untreated animals. However, p38/MAPK inhibitor SB203580 did not fully block the above-mentioned effects caused by colistin. Conclusion: Pre-administration of colistin could attenuate an excessive inflammatory reaction and protect the lungs from MRSA-associated damages. However, these effects could not be reversed by blocking the p38/MAPK pathway alone. Collectively, the mechanism underlying the immunoregulatory effects of colistin in mammals needs to be further explored.

Long-term aerobic exercise training-induced anti-inflammatory response and mechanisms: Focusing on the toll-like receptor 4 signaling pathway

Toll-like receptor 4 (TLR-4), which regulate inflammatory reactions, has become a popular research topic in recent years. This article reviews the latest scientific evidence on the regulation of TLR-4 by regular aerobic exercise training. The literature shows that long-term regular aerobic exercise training can effectively attenuate the expression of TLR-4 in immune cells and regulate its downstream intracellular cascade, including the p38 and PI3K/Akt signaling pathways. This further reduces cytokines secretion by inflammatory cells, which enhances immune system. We consider that the scientific evidence that long-term aerobic exercise training improves the inflammatory response provides a reasonable basis for using aerobic exercise training as a treatment for patients.

Immunomodulatory effects of colistin on host responses against carbapenem-resistant Klebsiella pneumoniae biofilms

Colistin (CST) is a last-resort therapeutic option for carbapenem-resistant Klebsiella pneumoniae (CR-Kp) infections in critically ill patients. The effect of subinhibitory CST concentrations (sub-MICs) on biofilm formation is organism-dependent. We investigated the interactions between CST and innate immune cells against CR-Kp biofilms (CR-KpBF) by studying the effect of biofilm sub-MICs of CST on (i) damage induced by human polymorphonuclear neutrophils (PMNs) on CR-KpBF and (ii) the immunomodulatory potential on human mononuclear cells (MNCs) exposed to CR-KpBF. The impact of CST on PMN-induced biofilm damage was assessed by XTT reduction assay. Signal transduction and gene expression profiles in response to CST sub-MICs of MNCs exposed to CR-KpBF were studied by RT-PCR and multiplex ELISA. Pre-exposure of CR-Kp to 0.06 mg/L CST led to subsequent increased PMN-mediated biofilm damage against CR-KpBF in the presence of CST biofilm sub-MICs: there was an additive effect at 2, 4, 8 and 16 mg/L. However, the overall biofilm damage was not >52%. MNCs responded to CR-KpBF through Toll-like receptor 2 (TLR2) by 2.5-fold upregulation and NLRP3 inflammasome activation. CR-KpBF stimulated increased production of interleukin 1-beta (IL-1β), tumour necrosis factor-alpha (TNFα), IL-8 and IL-6. In the combination treatment, 0.5 mg/L CST reduced IL-1β, TNFα and IL-8 levels, whereas at 2 mg/L and 8 mg/L it increased the anti-inflammatory cytokine IL-10 (P < 0.05). Biofilm sub-MICs of CST enhance PMN killing capacity and attenuate production of inflammatory cytokines by MNCs exposed to CR-KpBF, playing a potentially important immunotherapeutic role especially for patients with cytokine deregulation.